Recent Accounting Pronouncements - Additional Information (Detail) $ in Thousands		3 Months Ended
	Jan. 01, 2020 USD ($)	Mar. 31, 2020 portfolio	Mar. 31, 2020 numberOfLoanPortfolios	Mar. 31, 2020 USD ($)	Mar. 31, 2020 segment	Dec. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of distinct loan portfolios | portfolio		7
Current expected credit losses, initial loss forecast		1 year
Current expected credit losses, reversion period, term		2 years
Increase in allowance for loan loss	$ 54,619			$ 106,380		$ 54,619	$ 55,559	$ 55,461
Increase in allowance for credit losses on unfunded loan	2,656			8,950		2,656
Decrease in retained earnings	(682,185)			$ (649,909)		(682,185)
Noncredit discount amount accreted into interest income	11,800
Number of loan portfolios | portfolio		4
Number of loan segments			7		7
Impact of ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in allowance for loan loss	41,347
Increase in allowance for credit losses on unfunded loan	4,549					$ 4,549
Decrease in retained earnings	31,150
Impact of ASC 326 Adoption | Acquired Loan Portoflio
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in allowance for loan loss	$ 27,100